This invention relates to appliances for medical treatment and, more particularly, to an appliance collapsible for insertion into a human organ and capable of resilient restoration (which will be referred to as xe2x80x9cthe appliance to be implantedxe2x80x9d in this specification and claims), to a method of collapsing the appliance to be implanted, and to a method of using the collapsed appliance to be implanted into a catheter.
The artificial blood vessel is an example of the appliance to be implanted. At present, treatment of, for example, aortic aneurysm is conducted by implanting an artificial blood vessel. In particular, the portion of a blood vessel which has an aneurysm is removed by resection, and an artificial blood vessel is implanted in place of the resected portion and connected to the remaining blood vessel by suturing or the like.
The above-mentioned method of surgically implanting the artificial blood vessel for treatment of aortic aneurysm, however, is highly dangerous. Especially, an emergency operation for treatment of a ruptured aneurysm has a low life-saving rate, and an operation of dissecting aortic aneurysm is difficult to conduct and has a high death rate.
Therefore, in order to treat these diseases without a surgical operation, a method has been developed of introducing a catheter into an appliance such as an artificial blood vessel in collapsed condition into a human organ such as a blood vessel, and transporting the appliance to a desired position such as an affected or constricted portion thereof, where the appliance is released so as to be expanded and implanted there.
The appliance to be implanted is so constructed that a pair of end wire rings which are flexibly foldable and elastic are arranged to divide themselves, each of the end wire rings is connected by a tubular cover which is made of a sheet of flexible and tensile material and an intermediate wire ring is arranged between both of the end wire rings and fixedly connected to the above-mentioned tubular cover by suturing or with adhesive.
As a method of collapsing the appliance to be implanted, the following method is adopted in which a plurality of hooking means for a pull string to be passed are formed at every other dividing points each of which equally divides the circumference of the front end wire ring into an even number, the front end wire ring is folded into a wavy shape with the dividing points which are provided with a hooking means for a pull string forming forwardly directed peaks and the dividing points which are not provided with a hooking means for a pull string forming the bottoms of forwardly directed valleys, each of the intermediate wire rings and the rear end wire ring is folded into a wavy shape having the same phase as that of the front end wire ring and the whole artificial blood vessel is inserted into a catheter.
The above-mentioned intermediate wire ring is inevitable because of several points of view, such as it provides the artificial blood vessel with a capability of keeping its tubular shape so as to fit a human body when arranged at a bent position in a body, thereby to prevent the artificial blood vessel from being pushed downstream. However, if such an intermediate wire ring is attached to the tubular cover, the appliance is easily prevented from being folded. The reason is that the tubular cover tries to follow the movement of the front end wire ring with forming big wrinkles near the front end wire ring when the front end wire ring is folded into a wavy shape since the tubular cover is connected to the front and rear end wire rings at both end portions thereof. However, as the tubular cover is made of a sheet, the locally formed wrinkles do not bring about transformations at the center of the tubular cover. Therefore, for example, if the whole area of the circumference of the intermediate wire ring is fixedly connected to the tubular cover, the center of the tubular cover is dragged at the specified positions of the circumference thereof toward the direction of the peak or the valley along the wavy shape of the intermediate wire ring and the whole tubular cover tends to be bulky as well as unfavorable load is applied to the intermediate wire ring because of the sliding resistance. Therefore, the intermediate wire ring may be hindered from being folded into a small size with forming a regular wavy form because of distortion of the direction the intermediate wire ring is to be folded as well as of folding force. Even though the intermediate wire ring is fixedly connected to the tubular cover only at several points of the circumference thereof each of which is spaced apart, the points selected at random will cause sliding resistance from the tubular cover toward the peaks or valleys, thereby to provide no effective means to solve the problems.
In addition, the mutual interference between the intermediate wire ring and the tubular cover not only prevents the intermediate wire ring from being folded but also folds the appliance to be implanted imperfectly and insufficiently. Bent portion caused by the appliance to be implanted unnaturally folded will cut off the permanent function as a blood vessel. This also may hinder the movement of transporting the artificial blood vessel through a catheter and the function of the appliance to be implanted as it is intended to because of imperfect restoration of the appliance to be implanted even though the appliance to be implanted is released at a target portion.
On the other hand, the blood vessel is distributed variously in a body and, for example, an artery which comes from a heart is bifurcated at the groin of a thigh. If an affected part falls on the bifurcated part, the above mentioned cylindrical-shaped artificial blood vessel can not be used as it is, so that it is inevitable that an artificial blood vessel whose shape fits for such a shape of blood vessel should be developed. In addition, for implanting an artificial blood vessel in such a bifurcated part it is not enough just to transport the artificial blood vessel to a target position through a catheter and release it there. In this case, it is necessary to move the artificial blood vessel to be fit for a shape of the blood vessel at an target position after released, thereby requiring to develop a method of moving the artificial blood vessel.
The object of the invention is to solve all of the above-mentioned problems.
The appliance to be implanted in accordance with the invention is characterized by that comprising a front end wire ring, a rear end wire ring arranged facing to the front end wire ring, a tubular cover which connects the front end wire ring and the rear end wire ring, and a plurality of intermediate wire rings spaced apart from each other between the front end wire ring and the rear end wire ring, that each of the front end wire ring and the rear end wire ring and the intermediate wire rings are given flexibly foldable elasticity, that the circumference of the front end wire ring is equally divided into four or an even number over four, hooking means are formed for a front pull string to be passed through at every other dividing point and that the circumference of the intermediate wire ring is fixed to the tubular cover by suturing or with adhesive at the positions which correspond to the midpoints between each adjacent two of the dividing points of the front end wire ring.
The appliance to be implanted may concretely be represented by that a single rear end wire ring is arranged to face to a single front end wire ring, or that parallely arranged two rear end wire rings are arranged to face to a single front end wire ring and a bifurcated tubular cover connects the front end wire ring and two rear end wire rings with forming a Y-shape.
To improve the implanting state of the appliance to be implanted, it is effective that each of the front and rear end wire rings is circumferentially covered with an elastic protective material, thorns are provided on the circumference of at least one of the wire rings so as to stick into a human organ to be embedded therein, or a pole is provided to connect at least two adjacent wire rings.
The method of collapsing the appliance to be implanted in accordance with the invention is characterized by that the appliance to be implanted comprises a front end wire ring, a rear end wire ring arranged facing to the front end wire ring, a tubular cover which connects the front end wire ring and the rear end wire ring, and a plurality of intermediate wire rings spaced apart from each other between the front end wire ring and the rear end wire ring, that each of the front and rear end wire rings and the intermediate wire rings are given flexibly foldable elasticity, that the circumference of the front end wire ring is equally divided into four or an even number over four, hooking means are formed for a front pull string to be passed through at every other dividing point and that the circumference of the intermediate wire ring is fixed to the tubular cover by suturing or with adhesive at the positions which correspond to the midpoints between each adjacent two of the dividing points of the front end wire ring, and that the method comprises the steps of; folding the front end wire ring into a wavy shape with the dividing points each of which is provided with a hooking means forming forwardly directed peaks and the other dividing points forming the bottoms of forwardly directed valleys, and folding the intermediate wire rings and the rear end wire ring each into a way shape having the same phase as that of the front end wire ring, thereby to insert the whole appliance to be implanted into a catheter.
If the number of the dividing points are four, it is effective to pick the whole appliance to be implanted by forceps along a generatrix which passes two points facing each other on the front end wire ring and each of which is provided with a hooking means and then to insert the appliance to be implanted together with the forceps into the funneled tube from a big portion of the funneled tube toward a small portion thereof, and finally to pull the forceps out of the funneled tube.
The forceps may preferably be provided with serrate engaging member which lessens a sliding resistance between the appliance to be implanted and the forceps toward the direction to be pulled than that to be inserted.
For inserting an appliance to be implanted which has been kept in a collapsed condition into a catheter, it is effective that a pair of strings each of which has a loop at the tip thereof are provided for each of the wire rings respectively, that the strings are engaged with either one of the wire ring or the tubular cover at the positions of the circumference of each wire rings which correspond to the midpoints between two adjacent dividing points of the front end wire ring, and one of the strings is wound around the wire ring clockwise until it reaches the backward of the wire ring while the other string is wound around the wire ring counterclockwise until it reaches the backward of the wire ring, that a retaining rod is passed through the part at which each of the loops overlaps, and that each of the strings is tied each other so as to keep each of the wire rings in a collapsed condition. The retaining rod may preferably comprise a tube and a wire which is inserted into and passed through the tube. It is especially advantageous that after the wire rings are kept in a collapsed condition, the tube is pulled out so as to keep the collapsed condition by the wire alone.
For collapsing each wire rings into a wavy shape by inserting the appliance to be implanted into a funneled tube from a big portion of the funneled tube toward a small portion thereof, it is effective the appliance has previously been contained in a pipe member having a diameter which is bigger than that of the small portion of the funneled tube and smaller than that of the big portion of the funneled tube.
The method of using the appliance to be implanted in accordance with the invention is characterized by that the appliance to be implanted comprises a single front end wire ring, parallely arranged two rear end wire rings facing to the front end wire ring, and a Y-shaped tubular cover connecting the front end wire ring and the rear end wire rings, in order to implant the appliance to be implanted into a Y-shaped portion having two branches bifurcated from a single trunk a front hooking means is formed at the front end wire ring for pulling whole of the appliance to be implanted forward and a rear hooking means is formed at each of the rear end wire rings for pulling the appliance to be implanted rearward respectively, and that the method comprises the steps of; pulling the front hooking means of the front end wire ring toward the target portion to be implanted so as to transport the appliance to be implanted through one of the branches to the trunk, and then pulling each of two rear hooking means of the rear end wire rings so as to drag each of the rear end wire rings to one of the branches and to the other branch respectively.
For inserting one of the rear hooking means of the appliance to be implanted into one of the branches of a Y-shaped portion to be implanted and dragging it into other branch thereof, it is effective that a device for transporting an appliance to be implanted is attached to the rear hooking means of the appliance to be implanted so as to urge the appliance to be implanted rearward when the appliance to be implanted is transported to near the trunk through one of the branches and that the device for transporting an appliance which is attached to one of the rear hooking means of the appliance to be implanted is caught and dragged into other branch by a catcher which has been inserted into near the trunk through other branch.
For securely catching the device for transporting an appliance by a catcher, it is preferable that the device for transporting an appliance to be implanted which is to be dragged out of the body by a catcher is transported to a portion to be implanted through one of the branches with the front end of the device engaged with the rear hooking means, that the base end of the device is turned down and transported to the portion to be implanted through the same branch, and then the base end of the device is caught by the catcher.
For effectively preventing the device for transporting an appliance to be implanted from entangling in the appliance to be implanted, it is preferable to adopt a method that comprises steps of; arranging a guide pipe which has a valve at the base end thereof along one of the branches and into which the front end of the device for transporting an appliance has previously been inserted through a hole provided on the valve by being pushed to open the hole with making use of the elasticity of the hole, pushing the base end of the device for transporting an appliance which is turned down so as to be inserted into the guide pipe through other hole provided on the valve so as to open the hole with resisting the elasticity of the hole, and pulling the catcher which catches the base end of the device for transporting an appliance so that the two holes become continuous each other and the turned down portion of the device for transporting an appliance is contained in the guide pipe.
For making it easy to transport the appliance to be implanted it is preferable that a pair of strings each of which has a loop at the tip thereof are provided for each of the wire rings respectively, that the strings are engaged with the tubular cover at the positions of the circumference of each wire rings which correspond to the midpoints between two adjacent dividing points of the front end wire ring, and one of the strings is wound around the wire ring clockwise until it reaches the backward of the wire ring while the other string is wound around the wire ring counterclockwise until it reaches the backward of the wire ring, that a retaining rod is passed through the part at which each of the loops overlaps, and that each of the strings is tied each other so as to keep each of the wire rings in a collapsed condition.
For making use of the appliance to be implanted more generally even though the shape of the portion into which the appliance to be implanted is implanted varies it is effective to adopt a method of using the appliance to be implanted that at least two appliances to be implanted are prepared, that the front end wire ring of the appliance to be implanted which is inserted later locates in front of the rear end wire ring of the other appliances to be implanted which is inserted former, and that the appliance is connected to the adjacent appliance with each other partially overlapped at the adjacent position. In this case, it is especially preferable that the appliance to be implanted arranged downstream has a diameter which is smaller than that of the appliance to be implanted arranged upstream and the appliance to be implanted downstream is partially inserted into the appliance to be implanted upstream.
With the appliance to be implanted and the method of collapsing the appliance to be implanted in accordance with the invention, the operation of collapsing the appliance to be implanted can be conducted smoothly and the condition of which the appliance is implanted becomes satisfactory. In other wards, as the intermediate wire ring is collapsed into a wavy shape having the same phase as that of the front end wire ring, to put it in an extreme way each of the points on the circumference corresponding to the dividing points forms a peak of a mountain or a bottom of a valley formed between two mountains by taking turns while the positions corresponding to midpoints between each adjacent two of the dividing points move neither frontward nor rearward at all. As the intermediate wire rings are fixedly attached to the tubular cover at several points each spaced apart, the portions of the intermediate wire ring which bent most when being folded are free of the tubular cover. This makes the intermediate wire ring free from dragging resistance from the tubular cover, thereby to secure the free movement to be collapsed with ease. In addition, as the intermediate wire ring is collapsed into a wavy shape as well as the front end wire ring, the whole appliance is given a big folding rate, thereby to secure a compact collapsed state and good transporting movement through a catheter for a relatively bulky appliance to be implanted. In addition, in accordance with the arrangement, if the appliance to be implanted is released at a target position in a blood vessel, the dividing points are restored toward right-angled direction to the blood vessel, and the end portion of the appliance to be implanted certainly open and does not close the inner space thereof. This helps the appliance to be implanted to appropriately follow the movement of the constantly pulsating blood vessel with close adherence as well as improves a rate of successful implantation. The above-mentioned operation functions for not only a simple tubular shaped appliance to be implanted but also a bifurcated Y-shaped appliance to be implanted.
Elastic protective material circumferentially covering the wire rings of the appliance to be implanted is useful to prevent the inner wall of a human organ from being damaged by direct contact with the wire rings. The protective material also acts as a seal to attach both ends of the appliance to be implanted tightly to the inner wall of a human body, thereby to effectively prevent leakage of blood through the ends of the appliance when implanted.
When thorns are provided projecting from the wire rings, they stick into the inner wall of a human organ to be embedded therein so that the whole appliance is fixed to the human organ. Therefore, the thorns effectively prevent the appliance to be implanted from being displaced or even carried by blood flow downstream in a blood vessel.
It can effectively improve the tubular shape of the whole appliance to be implanted in the strength and the construction if at least two of the adjacent wire rings are connected by a rod.
If the number of the dividing points is four, it is extremely easy to fold the appliance to be implanted by using a pair of forceps. Namely, if the appliance to be implanted is inserted into the funneled tube with the whole appliance picked by forceps along a generatrix which passes two points facing each other on the front end wire ring each of which is provided with a hooking means, the points picked by the forceps are carried in advance from the big portion to the small portion of the funneled tube while other points approach each other with restrained by a tapered surface of the inner wall of the funneled tube from moving forward following the points having a hooking means. The points picked by the forceps inevitably form a peak of a mountain and the midpoints between two adjacent points picked by the forceps form a bottom of a valley, thereby to fold the appliance to be implanted into an appropriate wavy, shape. In this case, the intermediate wire rings are easily transformed to the direction so as to form a mountain and a valley with the points on the circumference of the intermediate wire ring corresponding to the midpoints between two adjacent dividing points on the front end wire ring serving as fulcrum, which makes the operation of folding the appliance smooth and appropriate.
In this case, if the forceps are provided with serrate engaging member, the pushing force applied to the forceps can effectively be transformed to a force of propelling the appliance to be implanted by making use of the serrations of the engaging member when inserting the appliance to be implanted, and the forceps can be smoothly withdrawn from the funneled tube without dragging the appliance to be implanted by making use of the serrations of the engaging member.
If the points on the circumference of the intermediate wire ring corresponding to the midpoints between two adjacent dividing points are tied by a pair of strings each of which has a loop at the tip thereof and a retaining rod is passed through the part at which each of the loops overlaps, the appliance to be implanted is kept in a collapsed condition. This makes it possible that the appliance to be implanted is inserted into a catheter without using a funneled tube. This also makes it easy to adjust the position at which the appliance is implanted because the appliance to be implanted can be kept in a collapsed condition after it is released from the catheter. This method is useful especially for the appliance to be implanted whose shape is bifurcated. In addition, if the retaining rod is pulled out, the loops overlapping each other are released from binding and free to move. As the portion at which the stings are sewed to the tubular cover is loosened, the force to keep the appliance to be implanted in a collapsed condition is released, and then the appliance to be implanted is restored to the original shape without bound by strings. In this case, as the strings are used as not a single but a pair, even though one of the strings might get stuck on the way, the appliance to be implanted is guaranteed to restore by another string.
If the retaining rod comprising a tube and a wire is used and the tube is pulled out with the wire left in a collapsed condition, the whole appliance to be implanted remains flexible with the wire functioning as the retaining rod. This makes it possible that the appliance to be implanted passes smoothly through the bent portion or the like when transported in a collapsed condition.
If the appliance to be implanted has previously been contained in a pipe member having a diameter bigger than that of the small portion of the funneled tube and smaller than that of the big portion of the funneled tube, it saves the operation of collapsing the appliance to be implanted. Just inserting the pipe member into the funneled tube so as to make abutting engagement with the inner surface of the funneled tube and pulling out the appliance to be implanted from the side of the front end wire ring enables the appliance to be implanted to be collapsed into a smaller size so as to be inserted into the small portion of the funneled tube and a catheter.
With the method of using the appliance to be implanted in accordance with the invention, a Y-shaped appliance to be implanted can effectively be transported to be implanted into a portion at which a blood vessel branches out into two, thereby to greatly improve the appliance to be implanted in use generally and practically.
In this case, if a catcher is inserted into near the portion to be implanted and catches a device for transporting the appliance which is attached to one of the rear end wire rings of the appliance to be implanted, it can be extremely easy to fix the appliance to be implanted into a bifurcated portion to be implanted.
If the front end of the device for transporting the appliance is engaged with the appliance to be implanted and the base end of the device for transporting the appliance is turned down so as to be caught by the catcher, it becomes easy to arrange the device for transporting the appliance at a position where it is easy for the catcher to catch. As a result of this, the accuracy and the efficiency of implanting the appliance to be implanted is effectively improved.
During the above process if a guide pipe having a valve is used, it becomes possible to guide the base end of the device for transporting the appliance to a position preferable to be caught with not only preventing bleeding but also preventing the device for transporting the appliance from entangling in the appliance to be implanted.
If a pair of the appliances to be implanted in accordance with the invention are connected to partially overlap, it can change the length of the connected appliances relatively freely by adjusting the length of the overlapped portion. This makes it possible to commonly use the same standardized appliances to be implanted for the organ into which the appliance is to be implanted even though the length or the shape of the organ varies a little. If the appliance to be implanted arranged downstream is partially inserted into the appliance to be implanted arranged upstream, not only both of the appliances to be implanted can be connected smoothly but also the appliance can be implanted satisfactory so as to fit the shape of the blood vessel into which the appliance is to be implanted because usually blood vessels are gradually smaller in diameter from upstream to downstream.